PROJECT SUMMARY/ABSTRACT Adolescents and young adults (AYA) with Type 1 Diabetes (T1D) are at risk for poor glycemic control, which in turn increases their risk for short- and long-term diabetes complications. These risks peak during the transition from pediatric- to adult-focused care, when care is subject to fragmentation and lack of coordination. AYA's risk of poor outcomes is simultaneously elevated by new expectations to independently manage their disease and treatment, but many lack the motivation to do so. This mentored career development award for Lauren Wisk, Ph.D., a pediatric health services researcher, will target this important area with the guidance of an outstanding mentoring team and with new knowledge obtained during targeted career development activities. In Aim 1, Dr. Wisk will use data from a large national health insurance plan (>45 million enrollees) to describe population- level utilization and outcome trends across the health care transition for AYA with T1D, and evaluate their determinants at individual and system levels; to achieve this aim she will gain new content knowledge of health care delivery systems and structures. In Aim 2, she will develop summaries of population data and use qualitative methods to engage AYA with T1D in evaluating those summaries for salience and acceptability for use in a patient-centered, behavioral intervention. Dr. Wisk will incorporate new skills in behavioral science and health communication as the foundation of this patient-centered intervention design to improve AYA's motivation to engage in transition preparation tasks. In Aim 3, she will undertake training in implementation and improvement science in order to implement the intervention, assess its effectiveness for motivating adoption of key transition preparation activities, and determine strategies to influence the full and effective use of the intervention in clinical practice settings. Dr. Wisk's K01 research to develop and implement a behavioral intervention trial to improve transition preparation for AYA with T1D will form the basis of a multi-site, longitudinal trial to be proposed in an R01 application submitted at the end of the K01 period. Dr. Wisk seeks to become an independent investigator with comprehensive expertise in designing, implementing and disseminating interventions for AYA with T1D during their health care and life-course transitions, with the additional long-term objective of translating these interventions into sustained improvements in self- management and health outcomes in T1D. Through the proposed career development award and accompanying training activities, she will integrate her training and research objectives to understand how AYA with T1D navigate the health care system during transition and what factors are most effective for motivating their continued health care engagement during that time, ensuring that she has the skills necessary to achieve her career goals. Dr. Wisk is uniquely positioned to use this award and the support of a highly skilled mentoring team and institutional environment to launch an independently-funded research career.